RUI: Geomorphology and Erosion of Extensional Mountain Blocks

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9317181 Harbor Geomorphic response to extensional uplift is a matter of concern to the geomorphologist, geophysicist, and sedimentologist, but has received little quantitative study. The area south of Yellowstone in the transition between the Basin and Range and Middle Rocky Mountains of Wyoming is dotted by extensional uplifts that exhibit a varying degree of structural offset and erosional dissection. the types of geomorphic processes and rates of erosion in several of these ranges will be studied in order to provide new data on redistribution of mass in the presence of major tectonic relief. The field area will also be numerically described in terms of relief and the dimensions/characteristics of drainage basins and stream segments, in part from DEM models of topography. Selected areas within these mountainous uplifts will also be mapped according to geomorphic process and studied in detail for rate of erosion. Using deposits that have accumulated on datable surfaces and incision or aggradation of streams over the last 103 to 104 years, the rate of processes on "competing" geomorphic components of mountain uplifts will be quantified. Deposits slated for study include pluvial lake deltas, debris fans, and valley fills behind landslide dams and moraines. All of these data will be used together to discover, if possible, the important predictors of denudation rate, such as relief or drainage area. Conceptual models of geomorphic processes will be evaluated against these data and also against descriptions of processes. Of particular interest is the change in rate of drainage basin erosion with time and increasing offset.